The petroleum industry has funneled billions of dollars into Canada's national, provincial and local economies and employs thousands of people in places with few other jobs. But the oil sands boom may also be polluting the air and water, and is stoking fear that it is damaging the health of those in its arc.

"From everything I hear from the indigenous peoples, their thinking seems to be 'It's a choice between whether we starve to death or are poisoned to death,'" said Dr. John O'Connor, a general practitioner who has worked here since 1993.